This application seeks support for a half-day symposium to be held at the 226th meeting of the American Chemical Society September 8-10, 2003 in New York City that is sponsored by the Division of Chemical Toxicology. The Symposium is titled: "Reactive Intermediates: The Vanguard" and seeks to focus on the latest novel chemistry relevant to chemical damage in human health. Certainly the complex etiology of many diseases, including cancers, is initiated by chemical damage to biomolecules; lipids, proteins and DNA. Over the last thirty years, considerable progress has been made in characterizing types of damage from a variety of sources both environmental and endogenous. While in some select cases, a reasonably straightforward picture of the underlying chemical events has emerged, it has become increasingly apparent that there is considerable chemical complexity in what ultimately constitutes damage that may affect disease. The initial, or primary, damage may in fact evolve in a series of subsidiary damage events. These subsidiary events may ultimately be responsible for, intensify or otherwise modulate the "initiating" event. Both the initial event and the subsidiary events are mediated by reactive intermediates. Understanding the fundamental aspects of the chemistry of these intermediates, their structure, reactivity and reaction products, is essential in dissecting the species that ultimately give rise to key damage events that devolve to the morbid state. The purpose of this symposium is to bring together leading chemists who are involved in the understanding the spectrum of primary and subsidiary reactive intermediates and the chemistry that gives rise to cellular damage that initiates disease, particularly cancer.